The invention relates to a tool for use by a pipefitter in welding to one end of a pipe a fitting having an internal shoulder. When welding such a fitting to a pipe it is common practice to thrust the pipe into the fitting until the end of the pipe abuts the shoulder. The welding operation should not take place with the pipe abutting the shoulder, however, because of the likelihood that the weld will crack or break due to thermal expansion and contraction of the pipe and fitting. Accordingly, proper practice requires the provision of a gap or clearance between the free end of the pipe and the shoulder of the fitting. Certain standards have been specified concerning the width of the gap that should be provided between the pipe end and the shoulder and most of these standards specify a gap of about 0.125 inch.
Various proposals have been made heretofore which make possible the provision of a gap of the required size between the shoulder of a fitting and the adjacent end of a pipe. For example, a widely used gapping tool is disclosed in Dearman U.S. Pat. No. 4,306,345. The proper use of such a tool provides an easy way of precisely locating a a pipe and a fitting in the proper relative positions prior to commencing the actual welding operation.
Even if the Dearman tool has been properly used, an external inspection of the pipe and fitting following the completion of the weld will not reveal to the inspector whether or not the proper gap exists between the pipe and the shoulder. This problem has existed for a great many years without a really effective solution having been found. What is believed to be the best solution heretofore proposed to the problem comprises the tool disclosed in Dearman copending application Ser. No. 486,565, filed Apr. 20, 1983, now U.S. Pat. No. 4,483,059. That tool includes a clamp and spacers similar to those associated with the tool disclosed in U.S. Pat. No. 4,306,345 and, in addition, includes a pair of manually manipulatable scribes which may be operated individually to inscribe the fitting and the pipe while the fitting is maintained with its shoulder in abutting engagement with the end of the pipe. Proper use of the two scribes will result in marks being placed on the fitting and on the pipe and the distance between the two marks will correspond to the spacing between the two scribes. Thereafter, the pipe and the fitting will be adjusted relatively to one another so as to enable the spacers to provide a gap of predetermined width between the fitting shoulder and the pipe end. This relative adjustment of the pipe and the fitting will result in an elongation of the distance between the two marks inscribed on the fitting and on the pipe. Thus, when an inspector measures the distance between the two marks, he will be able to determine from the spacing between the two marks whether a gap was or was not provided between the pipe and the fitting shoulder prior to the commencement of welding.
Although the tool illustrated in the above identified copending application makes possible the absence or presence of the gap to be determined from an external inspection, the operation of the tool is not as simple as is desirable. This is because the operator must maintain the fitting shoulder snugly against the end of the pipe while manipulating the scribes. Since both scribes must be manipulated, and since one hand of the operator usually is required to hold the fitting against the pipe, the operator can manipulate only one scribe at a time. Thus the inscribing of the pipe and the fitting takes longer than would be the case if both scribes could be manipulated simultaneously, and the inability to operate both scribes simultaneously leads to the possibility that one or the other of the scribes may not be operated at all, thereby rendering the tool ineffective for one of its intended purposes. Further, the necessity of having to operate the scribes individually and sequentially makes possible relative movement between the pipe and the fitting between scribing operations with the result that the inscribed marks may be so located as to prevent an accurate measurement being taken between them.
Appartus constructed in accordance with the disclosed invention retains the advantageous characteristics of the tools disclosed in the aforementioned patent and copending application and improves upon many of the operating characteristics thereof.